A basic service set (BSS) of Wireless Local Area Networks (WLAN) is generally as shown in FIG. 1, and generally includes one access point (AP) and multiple non-AP stations. At present, for a shared media wireless network, especially wireless local area networks (WLAN), in order to share transmission media and avoid interferences among multiple stations or multiple networks, a carrier sensing technology is generally utilized to determine whether a channel is occupied. The carrier sensing technology may be divided into two types: a physical carrier sensing and a virtual carrier sensing. The physical carrier sensing refers to determining whether received energy exceeds a certain threshold by means of wireless channel monitoring; and if the received energy exceeds the threshold, then deeming that the channel is occupied. The virtual carrier sensing refers to that the receiving and sending terminals send a wireless frame which carries a channel time (Duration) needing to be appointed for a subsequent transmission, other stations maintain a network allocation vector (NAV) locally according to the received appointment duration; and if the NAV of the station is not 0, then the station does not contend for die channel. In addition, the WLAN also defines other virtual carrier sensing mechanisms excluding NAV, such as a response indication deferral (RID), or a mechanism for maintaining a channel appointment occupied duration according to a time indication in a physical layer signaling.
At present. IEEE (Institute of Electrical and Electronics Engineers) standard organization has introduced parallel multi-user data transmission technology to solve the problem of WLAN network efficiency, which has drawn much attention and research, and many new wireless frames are designed to assist and accomplish multi-user data transmission. When the station receives these new wireless frames for multi-user transmission, especially the control frame for multi-user transmission, if continuing to use the original WLAN-defined virtual carrier sensing setting or resetting rules, some problems will be brought out mainly as follows.
1. The wireless frames for multi-user transmission, such as a multi-user request to send frame (MU-RTS. Multi-user Request to Send) and a trigger frame (TR, Trigger Frame), are broadcast frames mostly. Moreover, unlike from legacy broadcast frames, these broadcast frames require multiple destination stations to respond. When the wireless frame for multi-user transmission is received, such as the MU-RTS, the NAV setting rule of the destination station has a contradiction with the determination whether the station responds, and it needs to design a new virtual carrier updating rule.
2. The legacy device can only parse a part of new wireless frames for multi-user transmission, the current virtual carrier sensing rules may cause unfair contention between new devices and the legacy devices, and it should be avoided as far as possible that the new devices uses greedy rules that affect the transmission of the legacy devices.
In conclusion, in order to improve the network efficiency, the virtual carrier sensing is still a basic technology used in WLAN. However, many original rules are not applicable to the wireless frames designed for multi-user transmission. Therefore, it is necessary to design new virtual carrier sensing updating and resetting rules to guarantee that the new and old devices coexist well.
This section provides background information related to the present disclosure which is not necessarily prior art.